Organic laser dyes have found wide use in different fields of science and technology including spectroscopy, optics, and laser. These and other applications are discussed by T. W. Hansch in "Applications of Dye Lasers," chapter 5 of Dye Lasers, F. P. Schafer, ed. (Springer-Verlag, New York & Heidelberg, Berlin 1973). The lasing media based on organic dyes may be in the form of solids, liquids or gas. This lasing media causes spectral shifts of both absorption and emission and it affects photochemical stability. It also alters the distribution between processes that the excited states may undergo. For example, intersystem crossing where a molecule excited to the first excited singlet state may enter the system of triplet states and relax to the lowest level. Although polymers are the earliest and the most common solid state host for organic laser dyes, they are limited in their low photostability and low thermal stability. For example, incorporation of Rhodamine 6G in the mixture of MMA (methyl methacrylate) and PMMA showed a laser efficiency of 36%, but it was photounstable. Because of the poor thermal stability of the laser dyes, solid state dye lasers had been restricted to the polymeric hosts. Embedding organic dyes into a silicate glass would have significant advantages over the other types of matrices. Silicate glasses are photochemically inert and can enhance the thermal stability of most organic dyes. Sol-gel methods, with their low processing temperature, would make it possible to incorporate a dye into a transparent inorganic matrix.
There are many new water soluble, low threshold, fluorophoric laser dyes with good lasing characteristics, broad tuning ranges and superior photochemical stability. Therefore, it would be particularly desirable to incorporate organic laser dyes into a silicate glass host.